凝析气藏合理注气时机研究  

Proper gas injection time for the development of gas condensate reservoirs

作　　者：李骞[1,2] 钟兵[1,2] 杨洪志[1,2] 刘义成[1,2] 杨学锋[1,2] 

机构地区：[1]中国石油西南油气田公司勘探开发研究院 [2]国家能源高含硫气藏开采研发中心高含硫气藏工程研究所

出　　处：《天然气工业》2015年第10期78-83,共6页Natural Gas Industry

基　　金："十二五"国家科技重大专项"复杂碳酸盐岩气藏开发技术"(编号:2011ZX05015-003)

摘　　要：凝析气藏的开发方式主要分为压力衰竭式和注气保压式,而目前对于后者合理注气时机的研究甚少,不清楚什么时候注气最有利于凝析气藏的开发:若过早注气,注气量较大,经济效益较低;而过晚注气,则有可能导致凝析油污染严重,产能及采收率均较低。为此,选取某凝析气井的真实岩心,利用长岩心驱替实验研究其合理的注气时机;并在此基础上,运用响应曲面法和数值模拟的方法来综合评价合理的注气时间。研究结果表明:①对于凝析油含量较高的凝析气藏,应在地层压力降低至露点压力附近时进行注气,即可避免析出大量凝析油而导致气井产能和采收率大幅降低;②对于凝析油含量较低的凝析气藏,合理的注气时机为地层压力低于露点压力且高于最大反凝析压力区域,这样既能获得相对较高的凝析油采收率,又具有较高的经济效益。结论认为:对于凝析气藏的开发,注气越早开发效果越好,但不一定都能获得较高的经济效益。There are two main development modes for gas condensate reservoirs at present： depletion and gas injection. However, for the latter mode, little research was found on the reasonable gas injection time, that is, when should be the best time to commence gas injection. If ifs being too early, the volume of the injected gas will be too much to afford economically; if being too late, severe condensed oil contamination will be resulted and both gas productivity and ratio of gas recovery will he highly lowered down. In view of this, a real core was selected from a condensate gas well and the proper gas injection time was studied by use of long-core displace- ment experiments. On this basis, a geological model was established to study the issue by numerical simulation and response surface method. The following findings were obtained. As for rich condensate gas reservoirs, the optimal injection time is when the reservoir pressure is reduced to be about the dew pressure. This will prevent a larger volume of condensate oil from precipitating, avoiding a significant decrease of gas well productivity and gas recovery ratio. As for lean condensate gas reservoirs, the reasonable injection time is when the reservoir pressure is lower than the dew pressure but higher than the maximum condensate dropout pressure. This can not only obtain a higher condensate recovery, but achieve a greater economic efficiency. It is also concluded that the earlier the gas is injected, the better the development efficiency will be, but a high economic benefit will be uncertain as a result.

关 键 词：凝析气藏 注气保压式开采 注气时机 实验室试验 数值模拟 采收率 注气量 露点压力 经济效益 

分 类 号：TE372[石油与天然气工程—油气田开发工程]